We felt there was a real need for CFD with sufficient resolution, fidelity, quality; something better than a bit of RANS with a few turbulence model tweaks. Something on the subject of heat transfer, film cooling, blade tips, platforms, shrouds, leakage flow, because all of those things are related in some way, firstly to the heat transfer problem and the cooling problem, but also to the unsteady flow in a high pressure turbine system. We felt that we needed not only CFD but also experiments that go with that CFD; and again the problem with many experiments is that they tend to be RANS-type experiments. I am not trying to pre-judge the recommendations here, because I am not permitted to do that. But we need high quality experiments as well. The sort of situation where you might bring in PIV; where you are no longer looking just at the statistics of the flow, but at the quality and the quantity of the flow simultaneously. You will not only need things like PIV but also LDA, hot wires, Kulites, at the same time. Because we want to put the whole flow structure together. We want to understand what the key principles are that govern these unsteady flow problems. Why for example, the pressure side of the HP turbine rotor blade is still too hot, relative to what we would expect it to be. That's a key thing that was really driving this group. You'll need techniques like conditional sampling. It's no good just phase lock averaging the data, you'll just come up with periodic statistics. We need to take it further than that. Possibly - we don't know, therefore we need to go there to find out. There is also the strong feeling, and this goes back to Minnowbrook 1, 2, 3, and it is now here in Minnowbrook 4, that we need to understand more of what is really going into the turbomachinery components. I think last time we ended up with a recommendation that said we need to map out the full unsteady flow field in entire turbine HP, IP, LP system. I think we have watered that down a bit now, so that we do need to understand what goes into the HP system. Then coupled with high: fidelityCFD, or whatever, we can begin to at least evolve through the machine in terms of understanding the process further downstream. So that's heat transfer and unsteady effects.
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